DETERMINATION OF SOYBEAN SEED RESPIRATION RATE BY THE TITULATION METHOD

This trial was carried out under laboratory conditions, with three lot s of Iguacu soybean seeds, to determine the respiration rate by the ti tulation method. A randomized complete block design was used, with fou r repetitions, each one of them with 50 seeds and a control without se eds for each lot. The seeds were placed in gerbox with 40 mi of KOH 0. 1N, on distilled water wet blotting paper for fixing the CO2 produced by seeds respiration. The material was placed in germinator at constan t 25 degrees C for 16, 24 and 48 hours. After these periods, the titul ation of the fixative solution was performed with HCl 0.1N to check th e respiration rate. The most deteriorated seeds were those that presen ted the highest respiration rates, which were measured in mg of CO2/g of dry matter, when compared with the most vigorous lots. The titulati on method was suitable for the evaluation of soybean seed respiration rate because the final results separated the lots in three different q uality levels that were compatible with the results obtained from the accelerated aging and emergence.